1. Field of the Invention
The present invention relates to liquid crystal display (“LCD”) technology, and more particularly, to an LCD having an enhanced reflection ratio and a method of manufacturing the same.
2. Description of the Related Art
Liquid crystal displays are classified into a transmissive type LCD, a reflective type LCD, and a reflective and transmissive type LCD. The transmissive type LCD displays an image using an external light source, and the reflective type LCD displays the image using an internal light source, such as, for example, a backlight. The reflective and transmissive type LCD operates in a transmissive mode to display images by means of built-in light sources while indoors or in a dark place where an external light source does not exist. The reflective and transmissive type LCD operates in a reflective mode to display images by reflecting a light incident from an external light source outdoors or in a place where a high illumination is provided.
A reflective type LCD has an advantage in that it consumes less power than a comparable transmissive type LCD because it uses the external light source, and the reflective type LCD is widely used in LCD devices having a small to medium scale screen. However, the reflective type LCD has a disadvantage in that it uses a smaller quantity of lights than the transmissive type LCD so as to display images and fails to provide a high display quality.
Technologies to enhance the reflection efficiency for the external light source have been developed to overcome some disadvantages of the reflective type LCD. These technologies are mainly classified into i) a method of using a reflection layer with a high reflection efficiency, ii) a method of forming a diffusion layer by means of beads on the upper substrate (e.g., color filter substrate), and iii) a method of forming an embossing pattern on a reflection electrode of a lower substrate (e.g., thin film transistor substrate) so that direct lights incident from the front are scattered intentionally to maximize the reflection efficiency. The technique using the embossing pattern is important for enhancing the display quality because the reflection ratio depends highly on a slope of an embossing profile in the embossing pattern.
First, an organic insulating layer is coated with a substrate on which a thin film transistor (“TFT”) is formed so as to form an embossing pattern on a reflection electrode. The organic insulating layer is exposed and developed by means of a photo mask with a pattern. When the embossing pattern is formed on the organic insulating layer, the slope of an embossing profile in the embossing pattern can be regulated by an exposure amount irradiated onto a photosensitive organic insulating layer and by a successive heat treatment. However, when the technique using the embossing pattern is applied to an LCD with a large-scale screen, there may be non-uniformity of temperature distribution while curing the organic insulating layer, resulting in uneven or inferior heat treatment. Therefore, according to the conventional method in which the slope of the embossing profile is regulated by a condition of a heat treatment process, such as, for example, a hard-baking process for the organic insulating layer and a curing process, the uniformity of the slope of the embossing profile in the embossing pattern is reduced due to non-uniformity of the temperature distribution, thereby deteriorating display quality.